package com.container.demo;

import java.util.HashMap;
import java.util.Map;

public class HashMapTest {
    public static void main(String[] args) {
        Map<String,Object> map = new HashMap<>();
        map.put("1",2);
        System.out.println(map);

        //HashMap允许key、value值为空
        map.put(null,null);
        System.out.println(map);
    }
}
